KC-APP/client/app/lib/screens/chat_screen.dart

import 'package:flutter/material.dart';

import '../api.dart';
import '../main.dart';

/// Read-only chat view. Sending a message is a WebSocket-only path on the
/// backend (`chat:send`); wiring that up is a follow-up.
class ChatScreen extends StatefulWidget {
  const ChatScreen({super.key, required this.kcId});
  final String kcId;

  @override
  State<ChatScreen> createState() => _ChatScreenState();
}

class _ChatScreenState extends State<ChatScreen> {
  Future<List<ChatChannel>>? _future;

  @override
  void didChangeDependencies() {
    super.didChangeDependencies();
    _future ??= AppScope.of(context).api.channels(widget.kcId);
  }

  static const _typeLabels = {
    'GEMEINDE_GRUPPE': 'Gemeinde-Gruppe',
    'DIREKT': 'Direktnachricht',
    'LT_UEBERGREIFEND': 'Leitungsteam',
    'BROADCAST': 'Ankündigungen',
  };

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(title: const Text('Chat')),
      body: FutureBuilder<List<ChatChannel>>(
        future: _future,
        builder: (context, snap) {
          if (snap.connectionState != ConnectionState.done) {
            return const Center(child: CircularProgressIndicator());
          }
          if (snap.hasError) {
            return Center(
              child: Padding(
                padding: const EdgeInsets.all(24),
                child: Text('${snap.error}', textAlign: TextAlign.center),
              ),
            );
          }
          final channels = snap.data!;
          if (channels.isEmpty) {
            return const Center(child: Text('Keine Kanäle sichtbar.'));
          }
          return ListView(
            children: [
              for (final c in channels)
                ListTile(
                  leading: const Icon(Icons.tag),
                  title: Text(_typeLabels[c.type] ?? c.type),
                  subtitle: Text(c.id),
                  onTap: () => Navigator.of(context).push(
                    MaterialPageRoute(
                      builder: (_) => _ChannelMessages(
                        channelId: c.id,
                        title: _typeLabels[c.type] ?? c.type,
                      ),
                    ),
                  ),
                ),
            ],
          );
        },
      ),
    );
  }
}

class _ChannelMessages extends StatefulWidget {
  const _ChannelMessages({required this.channelId, required this.title});
  final String channelId;
  final String title;

  @override
  State<_ChannelMessages> createState() => _ChannelMessagesState();
}

class _ChannelMessagesState extends State<_ChannelMessages> {
  Future<List<ChatMessage>>? _future;

  @override
  void didChangeDependencies() {
    super.didChangeDependencies();
    _future ??= AppScope.of(context).api.messages(widget.channelId);
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(title: Text(widget.title)),
      body: FutureBuilder<List<ChatMessage>>(
        future: _future,
        builder: (context, snap) {
          if (snap.connectionState != ConnectionState.done) {
            return const Center(child: CircularProgressIndicator());
          }
          if (snap.hasError) {
            return Center(
              child: Padding(
                padding: const EdgeInsets.all(24),
                child: Text('${snap.error}', textAlign: TextAlign.center),
              ),
            );
          }
          final messages = snap.data!;
          if (messages.isEmpty) {
            return const Center(child: Text('Noch keine Nachrichten.'));
          }
          return ListView.builder(
            padding: const EdgeInsets.all(12),
            itemCount: messages.length,
            itemBuilder: (context, i) {
              final m = messages[i];
              return Align(
                alignment: Alignment.centerLeft,
                child: Container(
                  margin: const EdgeInsets.only(bottom: 8),
                  padding: const EdgeInsets.all(10),
                  decoration: BoxDecoration(
                    color: Theme.of(context).colorScheme.surfaceContainerHighest,
                    borderRadius: BorderRadius.circular(10),
                  ),
                  child: Column(
                    crossAxisAlignment: CrossAxisAlignment.start,
                    children: [
                      Text(m.body),
                      const SizedBox(height: 2),
                      Text(
                        m.createdAt,
                        style: Theme.of(context).textTheme.labelSmall,
                      ),
                    ],
                  ),
                ),
              );
            },
          );
        },
      ),
      bottomNavigationBar: const Padding(
        padding: EdgeInsets.all(12),
        child: Text(
          'Senden folgt (WebSocket) — aktuell nur Lesen.',
          textAlign: TextAlign.center,
          style: TextStyle(fontSize: 12),
        ),
      ),
    );
  }
}